Sorry. but were are NOT!!! commercial!!! :-p
only joking… I know
you have some links about Freifunk … be my guest and place them here 
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made a little mistake yesterday and my labpowersupply is dead now 
problem : can’t find schematic of this keithley 2200-72-1
this new siglent type looks like a nice replacement ( I don’t need 30-35 volts but I need/like 8 amps)
Why not ask for the schematic, or help on the EEVBlog-forum…
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buck / boost / buck-boost DCDC converters for higher currents (>2A)
cool … it works !
that’s good advise 
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Monochrome OLED Display Power Consumption
I previously did some measurements of OLED display power consumption in:
Big ESP32 + SX127x topic part 2
I removed the voltage regulators from four of the OLED displays (B, D, E and I, note that display numbering is not identical to my previous test) to see how much power consumption would drop when the display is switched off (from software) and the power consumption with display off dropped substantially (see column VReg removed). This difference is caused by the quiescent current of the regulator.
For some displays where the regulator is removed the power consumption when the display is on increases a little bit. This can be explained by the following: when the OLED board is provided with 3.3V supply voltage the display will get slightly less due to the regulator’s dropout voltage. When the regulator is removed there is no dropout so the display will get a slightly higher (3.3V) supply voltage.
All displays are blue, use I2C interface and use pin order GND, VCC, SCL, SDA. All
displays came with a XC6202 3.3V voltage regulator (code 662K) for 5V/3.3V operation.
From four displays the regulator was removed to minimize current usage when display
is off to make suitable for (3.3V based) low-power applications.
Disp off is display off/powersave/sleep.
Disp off VReg removed is after the 3.3V voltage regulator was removed from the PCB.
% pixels: display on and % pixels is the percentage of pixels that are lit.
Display Type Disp off Disp off 0% pixels 50% pixels 100% pixels
VReg removed
A 0.96" 128x64 13.7uA 1.4mA 8.7mA 11.4mA
B 0.96" 128x64 12.8uA 1.5mA 9.6mA 13.2mA
3.2uA 1.5mA 9.7mA 13.3mA
C 0.96" 128x64 7.7uA 1.6mA 14.7mA 24.3mA
D 0.96" 128x64 32.5uA 1.5mA 9.9mA 14.1mA
4.1uA 1.5mA 9.9mA 14.2mA
E 0.96" 128x64 7.0uA 1.5mA 16.4mA 29.4mA
1.2uA 1.5mA 16.7mA 30.2mA
F 0.96" 128x64 8.4uA 1.5mA 16.1mA 27.9mA
G 0.96" 128x64 7.0uA 1.5mA 9.9mA 13.2mA
H 1.3" 128x64 7.4uA 2.2mA 22.4mA 30.1mA
I 0.91" 128x32 8.3uA 2.2mA 16.7mA 21.8mA
1.2uA 2.2mA 16.7mA 21.8mA
J 0.91" 128x32 8.1uA 2.0mA 18.7mA 33.1mA
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are you still on holidays ? started missing you 
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Not anymore but I’m still in ‘holidays mode’ (and the temperatures are similar). 
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dangerous temperatures to work on electronics… a mistake is easily made, So take it easy 
a little bit a ‘special’ day today …
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The TPL5111 breakout is best when you have an enable pin you can control, the TPL5110 is best when you are able to ‘break’ the power input line to place the TPL5110 between the power supply and Vin.
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I have this idea of a ’ LoRaWAN enhanced’ Piggy Bank so children can see their savings on their iPad/mobile…
so I need a coin mechanism to detect what coin is inserted.
something like …
wow… they are big … 
- https://www.ebay.com/itm/Multi-Coin-Acceptor-Selector-Slot-for-Arcade-Gaming-Vending-Machine-Game-Control/163018818884
- https://www.ebay.com/itm/Multi-Coin-Acceptor-Selector-Mechanism-Vending-machine/250593770728
some analog versions
- what if I just weight the moment a coin is inserted ?
every coin has a different weight… and store (and transmit) the total
testing the principle
are these accurate enough ?
what comes after the 18650 (3400 mAh) ? the 26650 (5200 mAh) - test
dc/dc 5.1v power supply with 2x balanced/protected 26650
I’m moving my electronic (hobby) workshop to another room and I was looking online for material to make my own (bigger) workbench.
then I found this ‘used’ office outlet, just 10 minutes from my home and buying a used desk is almost cheaper then building it.
Anybody who needs (NL) an affordable hobby worktable… look
- so I bought 2 … now I get an 3.20 x 0.80 workbench …
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